1. Mrs. Butsch 8th Grade Science
Atoms and Elements
Mrs. Butsch 8th Grade Science

2. ATOMS
Atoms: The building blocks of all matter made up of protons, neutrons, and electrons.

3. Atoms
More than 2000 years ago the Greek philosopher Democritus ( B.C.) formulated the atomic hypothesis: All matter consists of smallest (indivisible) entities (atoms), separated by empty space. Combinations of the different kinds of atoms form all the things in nature.

4. Dalton's Atomic Theory
John Dalton's theory was based on the premise that the atoms of different elements could be distinguished by differences in their weights. He stated his theory in a lecture to the Royal Institution in The theory proposed a number of basic ideas:
All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occur when atoms are rearranged
Compounds are formed from atoms of the constituent elements.

5. Atoms Protons: Particles that have a positive electric charge.
Neutrons: Particles that have no electric charge.
Both Protons and Neutrons make up the Nucleus of an atom.

6. Atoms Electrons: Particles that have negative charge in an atom.
Electrons exist outside the nucleus.
Electrons orbit the nucleus of an atom.
The closer an electron is to the nucleus, the less energy it has. The farther away an electron is to the nucleus, the more energy it has.

7. Atoms
Protons
Neutrons
Electrons

10. Elements
Elements: Substances that are made of only one type of atom and cannot be broken down into simpler substances by normal chemical or physical changes.

11. Note the locations of the metals, halogens and noble gases.

12. C Elements Atomic Number: The number of protons in an atom. 6 12.011+
12.011
Carbon

13. Elements
Atomic Mass: The number of protons plus the number of neutrons in an atom 6 C
Atomic Mass
12.011
Protons Neutrons + n
Carbon

14. C Element Information 6 12.011 Atomic Number Symbol Atomic Mass
Number of Protons - + C -
Symbol n
Starts w/ a Capital + n n + - + - + + n n
12.011 +
Atomic Mass n
Protons Neutrons + n -
Name of Element
Carbon -
How do you determine the number of Neutrons ? n
Subtract the Atomic Number from the Atomic Mass 12 – 6 = 6 - = + n + n
How do you determine the number of Electrons ? -
In a stable atom, the number of protons equals the number of electrons 6 = 6 = + -